NMSFTP Xcode进度条

我现在正在使用NMSFTP框架工作几周

当文件上传到服务器时，我想在我的应用程序中添加一个进度条

如何从NMSFTP获得“进度”

                       let progressCallback = { (uploadedBytes: UInt) -> Bool in

                            // Update progress
                            let percentOfCurrentFile = Float(uploadedBytes) / Float(totalBytes)

                            return true // do not cancel the upload
                        }

                        // Upload
                        let uploadResult = sftp.writeFileAtPath(localFile.path!, toFileAtPath: "/"+remoteFile,
                                progress: progressCallback)